Electromotor-driven oil pump



Oct. 21, 1969 P. MARTINI ET AL 3,473,475

ELEGTROMOTOR-DRIVEN OIL PUMP Filed Oct. 25, 1967 2 Sheets-Sheet Inventors:

P I Ti e Qd KI O FSh (2 By fitter-r1255 Oct 21, 1969 P. MARTINI ET 3,473,475

ELECTROMOTORDRIVEN OIL PUMP Filed Oct. 25, 1967 2 Sheets-Sheet {L lm' ntar 5;

Paul Mar-him heodor- Nocon By w f tor/ways Unite States Patent O 54,898 Int. Cl. F04c /00, 15/04 US. Cl. 103-118 9 Claims ABSTRACT OF THE DISCLOSURE An oil pumping unit including a geared oil pump and an electric motor for driving the pump, the unit being provided with a rigid shaft member connected between the rotary portions of the motor and the pump and having only two bearings constituting the sole support for the shaft member.

BACKGROUND OF THE INVENTION The present invention relates to electric motor-driven oil pumps, and particularly to pumps for use in oil bumers for the feeding and atomizing of the heating oil. Such oil pumps have heretofore generally been constructed in the form of geared pumps. It is known that the drive shaft of such a pump must be disposed on the pump housing in an accurately centered position because unduly large tolerances and great deviations from center will result in greater play of the intermeshing gears and will thus impair the effectiveness of the pumping action. Additionally, the motor shaft must be centered in the motor housing to close tolerances so that the air gap will be kept at a minimum in order to attain a high rated output.

These requirements have previously been met by constructing the geared oil pump, as well as the motor, as independent structural elements each having its own bearings and its own carefully centered shaft. Both components were then connected by means of an elastic coupling. This coupling must be sufliciently flexible to compensate for any misalignments between the shafts to be connected.

The assembly of the motor, coupling and pump, when constructed in the conventional manner, however, results in a structure having an undesirably long axial dimension. Moreover, the total number of structural components is relatively large and their installation is expensive.

To overcome these disadvantages, it has already been proposed to eliminate the coupling and to construct the motor-geared oil pump assembly so that the pump shaft and the motor shaft form a rigid unit which is supported by bearings disposed at only two points. In such arrangement, one bearing is mounted in the pump housing while the other bearing is mounted in the motor housing and the pump and motor housings are connected together by means of a centering fitting. As a result, the motor shaft and pump shaft form a rigid unit rather than being elastically coupled in as flexible a manner as possible. For permitting the pump shaft and motor shaft to be constructed in the form of a rigid unit, double bearings for supporting each of the shafts are eliminated.

This arrangement has the advantage, on the one hand, of eliminating the need for a coupling and thus avoiding the expenditures for subsequently assembling the pump and motor and, on the other hand, of requiring only two bearings rather than the four bearings previously employed.

It has been found, however, that such an arrangement, in which the bearings are disposed in respectively different housings with the housings being connected together by means of a centering fitting, presents certain serious disadvantages. One primary disadvantage resides in the difficulty of achieving an accurate alignment of the shaft in both the motor housing and the geared pump housing. While the accurate alignment of the shaft in the pump housing is not of critical importance in the case of centrifugal, piston or roller vane pumps, it is, as has been mentioned above, of controlling importance for the proper operation of a geared pump.

SUMMARY OF THE INVENTION It is a primary object of the present invention to overcome these drawbacks and difiiculties.

Another object of the present invention is to enable the common shaft to be accurately aligned in both the pump housing and the motor housing.

Yet another object of the present invention is to permit such alignment to be accomplished in a simple and efiicient manner.

A still further object of the present invention is to simplify the installation of such a geared oil pump assembly.

These and other objects according to the present invention are achieved, in a geared oil pump for feeding fuel oil for atomization in an oil burner installation, an electric motor for driving the pump, a rigid shaft member connected between the rotary portions of the motor and the pump and constituting both the motor output shaft and the pump drive shaft, and shaft bearing means composed of only two bearings supporting the shaft member and constituting the sole support therefor, by the improvement composed of a common support housing for both the motor and the pump, the housing directly supporting both of the bearings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a cross-sectional view of an electric motor-driven oil pump according to the present invention in which one bearing is disposed in the motor and the other bearings is disposed in the pump, the pump and the motor having a common housing member.

FIGURE 2 is a similar View wherein both bearings are disposed in the motor and the pump housing is centered in a bearing plate of the motor.

FIGURE 3 is a similar view of a hermetically closed structural unit in which the motor interior is not sealed against the entrance of pump oil, the motor is of the external rotor type, and both bearings are disposed in the pump housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGURE 1 shows an arrangement in which a pump housing 2 is closed by a cover 1 and is simultaneously constructed to be the bearing plate 3 of an electric drive motor 4. A sleeve bearing 5 is disposed in the pump housing 2 and a ball bearing 6 is disposed in a flange bearing plate 7 for the motor, which plate is at the opposite end of the motor from plate 3. The sleeve bearing 5 is lubricated by the oil pumped by the oil pump disposed in housing 2. The motor and pump have a common shaft 8 and the motor interior is sealed, at the shaft 8, by a sealing member 9 which prevents the entrance of oil into the motor. The free shaft end 10 is provided for the connection of an additional piece of equipment, for example, a blower wheel for oil burner assemblies. The bearings 5 and 6 and the sealing member 9 may be con- 3 stituted by any well-known, commercially available components.

In FIGURE 2, the bearing 5 of FIGURE 1 is, in effect, replaced by a ball bearing 11 which is here disposed in the motor bearing plate 3 at the end adjacent to the pump, while fiange plate 7 carrying bearing 6 is connected to, and forms a part of, plate 3. The sealing member 9 is disposed in front of both bearings so as to be between the pump and the motor. The bearing plate 3 of the motor 4 and the pump housing 2 are constructed as separate structural components and are firmly and rigidly connected to each other by means of a centering fitting 12 such that the motor and pump are centered along the axis of shaft 8. The elements 2 and 3 could, of course, be of one piece as shown in FIGURE 1.

In the particularly advantageous embodiment of the present invention according to FIGURE 3, both bearings 5 and 13 are housed in the extended neck 14 of the pump housing 2. The starting motor, including the internal stator 15, the one-piece shaft 8", and the cup-shaped external rotor 16, is disposed in an area which is sealed by the sealing ring 17 and closed hood 1-8 against the entrance of oil from the outside.

Sealing the motor interior against oil coming from the oil pump is not necessary. On the contrary, it is advantageous to have the motor interior filled with oil because this results in an improved cooling effect, which can be increased by causing a continuous stream of fresh oil to flow through the motor. This can be achieved, for example, by providing a connection (not shown) either for a suction line or for an oil discharge line in the sheet metal hood 18. In the latter case the housing must be enclosed so as to be pressure-tight towards the outside.

The pump housing 2 is provided with either suction or discharge openings communicating with the motor interior. The internal stator of the external rotor-type motor can be very easily force-fitted onto the extended neck 14 of the pump housing 2. A rigid attachment can be achieved in any manner desired, for example, by glueing or by a pressure fit. The supporting flange 19 of the external rotor 16 is preferably constructed in the form of a closed cup having a smooth surface in order to avoid friction losses with the oil in the motor interior.

Either the oil may flow from the suction line through the opening 20 of the sheet metal hood 18, through the motor interior and then through the opening 21 into the pump housing 2, or the opening 20 of the sheet metal hood may be connected to the oil discharge line. Then the oil is pressed out of the opening 21 of the pump housing 2 into the motor interior and leaves the motor by the opening 20.

The common shaft can advantageously be made of one piece. It ispossible, however, to firmly fit the pump shaft into the motor shaft. Either form of construction can be employed for the embodiments of FIGURES 1 and 2.

The two bearings can be arranged in different ways. According to one possibility, the bearings can be disposed to respectively opposite sides of the motor rotor and the bearing adjacent the pump can be provided with a seal in the region between the pump and the motor to prevent oil from penetrating into the motor. When this arrangement is employed, the additional components of the geared pump can be installed after assembly of the motor portion, the motor being operative even before the pump components have been so installed.

Conversely, it is also possible to dispose both bearings within the pump, to mount them on a projection of the pump housing, and to seal the shaft end furthest from the pump against the pump oil. This latter solution ofiers particular advantages in conjunction with an external rotor-type motor of the type shown in FIGURE 3.

In either case, it is possible to first fabricate a basic structural unit composed of either the motor portion or the pump portion together with the shaft bearings and the common shaft so that it is subsequently necessary to connect only the remaining components of the other portion. This procedure substantially facilitates the overall assembly operation.

A further development of the present invention of substantial significance results when the motor and pump are constructed as a unit which is hermetically sealed against the leakage of oil. In this case all measures for sealing the shaft against pump oil leakage can be eliminated. The pump oil serves to lubricate both bearings and the cooling of the motor will be substantially improved when it is penetrated by the pump oil.

This cooling effect can be advantageously augmented if the oil pumped by the pump is caused to flow completely through the motor. For this purpose the motor should be enclosed in a pressure-tight casing. Particularly when an external rotor-type motor is being used, the encapsulation can be realized, as shown in FIGURE 3, by a sheet metal cover which is pulled over the motor like a hood and which is fastened to the pump housing on one side via a sealing ring.

The intense cooling effect of the pump oil available to the motor interior makes possible the use of a shadedpole motor, since its relatively high heat losses can easily be dissipated. Since furthermore no torque-absorbing shaft seal is required, a shaded-pole motor will provide sufficient starting torque. Thus the motor of FIGURE 3 would be of the shaded-pole type.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

We claim:

1. In an oil pumping unit including a geared oil pump for feeding fuel oil for atomization in an oil burner installation, an electric motor for driving the pump, a rigid shaft member connected between the rotary portions of the motor and the pump and constituting both the motor output shaft and the pump drive shaft, and shaft bearing means composed of only two bearings supporting the shaft member and constituting the sole support therefor, the improvement comprising a common support housing for both said motor and said pump, said housing directly supporting both of said bearings.

2. An arrangement as defined in claim 1 wherein said motor is disposed in a housing and both of said bearings are mounted in said housing, said arrangement further comprising sealing means disposed between said pump and said motor for sealing the bearing nearest said pump against the leakage of pump oil.

3. An arrangement as defined in claim 1 wherein both of said bearings are disposed in the portion of said housing associated with said pump, said arrangement further comprising sealing means disposed around that end of said shaft which protrudes from said pump for sealing said motor against the leakage of oil from said pump.

4. An arrangement as defined in claim 1 wherein the end of said shaft member furthest from said pump extends beyond said unit for connection to a further rotary unit.

5. An arrangement as defined in claim 1 further comprising a hermetically sealed enclosure enclosing both said motor and said pump and preventing the leakage of oil, and wherein said pump and said motor are in communication for premitting the passage of oil being pumped through the interior of said motor and the motor windings.

6. An arrangement as defined in claim 5 wherein said enclosure includes a sheet metal cover enclosing said motor and fastened to said housing, and a sealing ring disposed between said cover and said housing for sealing the interior of said motor.

7. An arrangement as defined in claim 5 wherein said motor is of the shaded-pole type.

8. An arrangement as defined in claim 1 wherein said 5 unit is arranged for permitting said pump to produce a flow of oil through the interior of said motor.

9. An arrangement as defined in claim 3 wherein said motor is of the external rotor type and said housing portion associated with said pump has an elongated neck on which the stator of said motor is mounted.

References Cited UNITED STATES PATENTS 6 Morrill. Gould et al.

Lawrence Phelps. Nicoll. Mieville. Turk. Seyler.

10 ROBERT M. WALKER, Primary Examiner 

